| ZCOM C I/F Library Routines |
| ZSEND (3X) |
- returned status (for response messages) | |
- protocol tag value (for terminal ZLU only) |
If Bit ZCOM_ZSEND_NOMX (0x4000) of mode is set and the request is to a
The ZCOM_ZSEND_MHD and ZCOM_ZSEND_NOMX bits are intended for use by multiplexing programs to intercept terminal messages and build specific messages or responses as required.
They can cause strange ZCOM subsystem behavior if used improperly; hence, they must be used with caution.
If bit ZCOM_ZSEND_LPR (0x0080) or ZCOM_ZSEND_XPS (0x0040) is set and the request is to a terminal, then the message will be queued on the low priority or express transmit queue, respectively. Otherwise, it defaults to the high priority queue.
The different transmit queues allow the caller to have some control over the order of messages being sent. The express queue is always processed first and is not bounded by queue limit. It is intended for sending critical control data and should never be used for normal data. The high priority queue is subject to queue limit checks and is intended for sending normal data. The low priority queue is processed only after all express and high priority messages are sent and is also bounded by queue limit checks. It is intended for sending data in a background mode. For a busy terminal, low priority messages will not be sent until all its higher priority activities are completed.
Chapter 4 | 311 |